Exploring the behaviour of water in glycerol solutions by using delayed luminescence

" Many properties of water have been related to the interplay between two distinct and interconverting structural species, namely the low-density water (LDW) and the high-density water (HDW). Supported by the results obtained with other aqueous solutions, this paper deals with the possibility of using the ultra-weak delayed luminescence (DL) to investigate water structuring in a mixture with glycerol." {Credits 1}

" It has been suggested that liquid water consists of two kind of micro-domains of rapidly exchanging polymorphism in dynamical equilibrium [5–12]: one form, namely the low-density water (LDW), with intermolecular hydrogen bonds like that of ordinary hexagonal ice, and the other one, namely the high-density water (HDW), with compact bonding similar to ice II." {Credits 1}

" ... luminescence from water, that is related to the structure of water, must be taken into account. Indeed Lobyshev et al. [52] observed an intrinsic luminescence from water, whose emission spectrum had a peak in the blue region (more precisely at 410 nm) if excited at 310 nm. After investigating also the luminescence from high diluted aqueous solutions of “luminescent” and “non luminescent” substances, they assessed that “although the lifetime of a single hydrogen bond is very short, water at each moment of time constitutes an infinite structure containing ordered clusters and disordered regions like a crystal with defects”. In such a way, the hypothesized dynamic quasi-lattice of water should support the transfer, over a chain of hydrogen bonds, of the absorbed energy from the excitation site to the defects which act as source of luminescence." {Credits 1}

" Nevertheless, these results are in some way puzzling: how it is possible that the excited states generating the DL exhibit so long lifetimes? Such a states come out from the hydrogen bond network existing between water and glycerol molecules and their lifetimes are more than six order of magnitude larger than the supposed lifetime of single hydrogen bond. A possible solution is to hypothesize the presence of collective states able to survive as topological singularities for very long times." {Credits 1}

{Credits 1} 🎪 Grasso, R., Musumeci, F., Gulino, M., & Scordino, A. (2018). Exploring the behaviour of water in glycerol solutions by using delayed luminescence. PloS one, 13(1), e0191861. © 2018 Grasso et al. This is an open access article distributed under the terms of the Creative Commons Attribution License.